1. Field of the Invention
This invention relates to the production of ready-to-eat shredded cereal products and to shredded cereal products.
2. Description of the Prior Art
Several processes are known for the production of ready-to-eat breakfast cereals which are in shredded form. Tempering of the cooked grains prior to shredding has been considered necessary for obtaining strong continuous shreds. In U.S. Pat. Nos. 548,086 and 1,159,045, cooked wheat or similar grains are subjected to tempering times of over 12 hours before shredding. As described in U.S. Pat. No. 4,179,527, in the manufacture of a whole wheat food product such as shredded wheat, whole wheat is cooked sufficiently to gelatinize the starch.
Gelatinization is a function of water penetration into the whole berry, temperature, and time, for a given type of grain. According to U.S. Pat. No. 4,179,527, the gelatinization of wheat starch involves a destruction of bonds in the crystalline regions of starch granules. Retrogradation is the return of the starch molecules to a crystalline structure, which is different from the original crystalline structure, upon cooling. Tempering permits the gelatinized wheat starch to slowly cool and permits water migration through the wheat particles to achieve a uniform water distribution within the particles. Retrogradation occurs during tempering. As reported in U.S. Pat. No. 4,179,527, if shredding is attempted shortly after cooking, the insufficient degree of retrogradation or tempering results in at best, short non-continuous strands and/or strands which are tough, curly, or suffer from other physical or textural disadvantage. In U.S. Pat. No. 4,179,527, the time required for the tempering of cooked whole wheat is substantially reduced by chilling the wheat at a temperature of from 1.degree. C. to about 12.degree. C.
Processes wherein tempering is not specifically mentioned or is indicated as being optional in the production of cereals from wheat or other grains, are disclosed in U.S. Pat. Nos. 1,189,130, 1,210,589, 2,008,024, 1,946,803, and 502,378. In U.S. Pat. No. 1,189,130, bran, such as wheat bran, is mixed with up to 50% of whole wheat or other gelatinous cereal flour, and is cooked in pans in a stream retort. The cooked product is dried to form lumps and the lumps are then fed through shredding mills. In U.S. Pat. No. 1,210,589, a composite cereal product is formed by mixing bran, shredded wheat, and syrup, molding the mixture and then baking it. In U.S. Pat. No. 2,008,024, a cereal biscuit is prepared by steaming or boiling wheat, surface drying the cooked product, and then converting it into a thin ribbed sheet. The shredding rolls are spaced sufficiently apart so that a sheeted material with ribs is obtained instead of a shredded product. In U.S. Pat. No. 1,946,803, rice, alone or in combination with bran, is steam cooked, dried and cooled to a rubbery consistency and optionally held for tempering to effect a uniform water distribution. This product is then passed between grooved rollers to form long flat ribbons. These ribbons are dried to produce a brittle product which is broken and then puffed by toasting. In U.S. Pat. No. 502,378, a cereal grain is prepared for shredding by boiling, steaming, steeping or soaking. Depending upon the spacing between the rollers, a product in the form of threads, lace, or ribbons, or sheets, and the like, is obtained.
Processes for the production of shredded oat cereals wherein considerable tempering is used, as in the conventional process for the production of shredded wheat, are disclosed in U.S. Pat. Nos. 1,170,162, 1,197,297, and 4,004,035. Tempering of cooked oats is also disclosed in U.S. Pat. No. 3,733,206. However, in the process of the latter patent, the biscuits contain flaked compacted cereal grains as opposed to shreds. In U.S. Pat. No. 1,170,162 and in U.S. Pat. No. 1,197,297, the whole berry is pulverized so as to permit flavoring ingredients to be incorporated in the final product. A dough is formed from flour, flavoring, and water. The dough is then cooked, rolled into slabs and then atmospherically dried for a period of 24 to 40 hours. The dried product is toasted, broken into pea size pieces and then shredded. In U.S. Pat. No. 4,004,035, it is disclosed that during the continuous production of shredded biscuits using a press type cutter or rotating contact cutter, to sever the web across the shreds, the tensile strength and stickiness of the shredded material limits the ability of these cutting devices to perform satisfactorily. The shredded material, it is disclosed, tends to adhere to the blade or the blade will not completely sever it. In U.S. Pat. No. 4,004,035, the shredded biscuits are formed by depositing a layer of shredded cereal in zig-zag configuration on a moving belt and then severing the material. However, tempering for a considerable amount of time as in these processes, is undesirable from the standpoint of equipment costs, plant efficiency, and excessive microbial growth. Furthermore, it has been found that when cooked whole oat groats are tempered prior to shredding, shreddability decreases. The deleterious effect of long tempering times upon the shreddability of oats is unexpected in view of the art-taught need to temper wheat to enable its shredding.
Processes for the production of cereal products made from oats without any apparent tempering step, are disclosed in U.S. Pat. Nos. 897,181, 3,062,657, 3,462,277, 3,732,109, and Canadian Pat. No. 674,046. In U.S. Pat. 897,181, the oats are wetted but not cooked and then passed repeatedly between grooved rollers and then baked. The boiling or steaming of the grain, it is disclosed, produces considerable change in the chemical quality of the grain and a number of the nutritious soluble elements escapes from the grain to the water. In the processes of the remaining patents, a shredded product is not produced by means of shredding rolls. In U.S. Pat. No. 3,062,657, flour and water are mixed to form a dough in an extruder. The dough is cooked in the extruder and then tempered in the extruder at a lower temperature. The extrudates are cut into pellets to simulate cooked and dried grains such as corn grits, whole wheat berries, oat groats, rice and the like. The extrudates, it is disclosed, have a moisture content ideal for flaking. It is generally on the order of 18 to 24% by weight, the moisture being uniformly distributed throughout so that the necessity for tempering is entirely eliminated and the extrudate can be immediately transferred to a flaking operation. It is disclosed that it is preferable to further cool the extrudate before it enters the flaking device to optimize flaking properties.
In U.S. Pat. No. 3,462,277, a mixture of flour and water is passed through an extruder to gelatinize the starch while the dough is cooked and transformed into a rubber-like mass. The moisture content of the mixture is 13 to 35%. The continuous U-shaped extrudate is pinched off into segments by cutting rolls to form canoe-shaped cereal products. The separated canoe-shaped pieces are then dried to below 15% moisture.
U.S. Pat. No. 3,732,109, discloses the production of a ready-to-eat oat cereal biscuit by subjecting an oat flour-water mixture to a water boiling temperature and superatmospheric pressure to gelatinize a portion of the starch in the oat flour. The mixture then passes through an orifice and the extruded product is cut into small pieces. The flake-shaped pieces which are formed are dried to a moisture content of from about 2% to about 6% by weight water. The dried flakes are then subdivided, admixed with a syrup, and compacted into the form of a biscuit. The formed biscuits are then dried to a moisture content of from about 4 to 5% by weight.
In Canadian Pat. No. 674,046, a shredded dry oat cereal product is produced without the use of shredding rolls. A dough is cooked in a screw extruder, extruded through orifices to form a strand bundle, and the strand bundle is cut into pieces by a cutting device which may be a pair of rolls.
In the production of a shredded oat cereal by means of shredding rolls, obtaining the cooked oats in a form which will produce continuous shreds is only one of several problems which are encountered. When oats are cooked atmospherically in water, an oatmeal-type product is obtained which sticks excessively to material handling equipment, such as conveyor belts and hoppers, as well as to the shredding rolls. Drying of the cooked product prior to shredding does not solve this problem. Stickiness is experienced upon transport to the dryer. Moreover, when water cooking is limited in time to reduce stickiness, shreds produced from the oats contain white streaks.
Oat groats, as well as oat flour, contain oat gum. The gum, as reported by Shukla, T., "Chemistry of Oats: Protein Foods and Other Industrial Products", Critical Reviews in Foods Science and Nutrition, pps. 383-424 (October 1975), is soluble in water at ambient temperature and is believed to be responsible for the gelatinous property of oatmeal. The cooking of oat groats atmospherically in water results in excessive extraction of the gums from the interior of the oat groat to the surface. The presence of the oat gums at the surface impedes the penetration of water into the oat groat for gelatinization of the oat starch.
Additionally, white streaks are also produced by overcooking the oat groats. It is believed that overcooking either results in bursting of the starch granules to expose white materials or results in a reaction product which is white. It has also been found that pressure cooking the oat groats with steam so as to provide a moisture content in the cooked groats which is sufficiently high to obtain a shreddable product also results in the development of white streaks.
Cooking to eliminate white centers in grains is taught in U.S. Pat. No. 2,421,216. Particles of cereal grains such as corn, rye, wheat, bran, rice, or oat groats are composited with particles of de-fatted soya beans in the form of grits, flakes, or meal to enhance the protein content of the cereal by use of a two-stage pressure cooking step.
The cereal grain is first cooked with flavoring solution in a rotary steam cooker. The cooker is maintained at from about 15 to about 20 lbs. steam pressure. Means are provided for the admission and discharge of steam, so as to permit the cooking to be carried out at a temperature of from about 250.degree. F. to about 260.degree. F. The flavoring solution is an aqueous solution containing about 8% sugar, 3.5% salt, and a small percentage of malt extract. The amount of the flavoring solution which is added to the cereal grain particles is in proportion to the original moisture content of the cereal grain. It is added in an amount so that the amount of moisture in the particles on leaving the cooker is from about 30 to about 45%. The de-fatted soya is separately tempered with about one part by weight of flavoring solution to about 3 parts by weight of de-fatted soya bean particles so that all of the solution becomes absorbed by the de-fatted soya bean particles. The cooking of the cereal is interrupted for the addition of the tempered soya. The cereal and the tempered soya are then cooked under substantially the same conditions of steam pressure to which the cereal was subjected during the initial cooking period.
The total cooking period to which the cereal component is subjected to should, according to U.S. Pat. No. 2,421,216, be such that the starches are hydrolyzed and highly dextrinized and the particles superficially gelatinized with no free starch or white center. The cereal particles, it is taught, should also have a light adhesive action on the intermediately added soya bean particles. The mixed mass of cereal and soya which is removed from the cooker, has a moisture content from about 30 to about 45%. This mass is then dried to a moisture content of from about 24 to about 32% using air at about 130.degree. F. The dried mass is then tempered for about 15 to 30 minutes before shredding in a shredding mill wherein the particles of soya become substantially uniformly spread out over and mixed with the cereal particles and adhered thereto by pressure through the shredding rolls. The shredded product is cut on a rotary cutter, dried on a rotary drier to about 20 to 28% moisture, dried in an oven to about 7 to 15% moisture content, and toasted to a moisture content of about 2.5%. From about 15% to as high as about 40% of de-fatted soya bean particles, based upon the weight of soya bean and cereal is used.
According to U.S. Pat. No. 2,421,216, the soya must be de-fatted so as to permit proper processing or good shredding in the mills. The de-fatted soya, which adheres to particles of the cereal, is believed to provide strength to the shredded product thereby enabling continuous shredding. In the case of oat groats, in Example V, the oat groats are first tempered, steamed and bumped or deformed prior to cooking them in the pressure cooker. This pretreatment would increase surface stickiness, which is desired for adhesion of the soya particles to the oat particles. It is believed that the soya particles, in adhering to the particles of cereal, tie up the sticky gums and starches on the cereal thereby reducing adhesion of the cereal particles to the material handling equipment.
The two-stage cooking of cereal grains is also disclosed in U.S. Pat. Nos. 3,512,990 and 3,787,584. In the process of the former patent, the dough, made from farinaceous materials such as wheat, corn, oats, rice potatoes, or legumes, is optionally partially or completely cooked with added moisture, to an approximate moisture content of about 30%. After this cooking step, the mixture is rendered homogeneous by passing it through an extruder, for example. The extruded product is dried to an approximate moisture content of 22 to 24%. The dried dough is then compacted between two rolls to provide a shredding effect and produce a sheet of dough having diamond-like regularly spaced perforations. The sheet of dough is then severed into strips, folded to form small biscuits which are closed on three sides and then deep fried.
In U.S. Pat. No. 3,787,584 an emulsifier free instant-type corn grits food product is produced by heating a mixture of corn grits, water and polysaccharide gum in a critical temperature range for a critical time period. The heated mixture is then heated in a second heating step which consists of a critical temperature range. The mixture is dried as a thin sheet on a drum dryer and then the cooked, dried sheet is comminuted. The first heating step is conducted at a temperature of from 60.degree. C. to 80.degree. C. so that the starch does not "set" or does not substantially gelatinize. In the second heating step, the mixture is heated to a temperature of from 90.degree. C. to 100.degree. C. The heated mixture is dried within 2 minutes of the time that the second heating step is accomplished. Polysaccharide gums, it is disclosed, are also used in the production of instant oatmeal.
In U.S. Pat. Nos. 987,088, 1,019,831, and 1,021,473, corn or another grain is ground and immersed in an amount of water which is limited to that which will be taken up by the grain during cooking. The purpose of this is to preserve in the cooked article the aroma and other properties of the grain which might otherwise be carried off or dissipated by the evolution of steam or vapor. In these processes, the cooked dough is extruded through a perforated plate to obtain filaments. However, in the production of a shredded oat product, if the moisture content of the oats is too low, either because of cooking in an insufficient amount of water or because of drying after the cooking step, consistent production of continuous shreds on shredding rolls cannot be achieved.
The present invention provides a process for the production of ready-to-eat shredded oat cereals made from whole groat oats alone or in combination with other cereal grains which have the shredded appearance and texture of shredded whole wheat. The cooked and cooled oats are in the form of discrete, individual or non-interconnected particles, which have good flowability through material handling equipment, do not exhibit a "tunneling effect" when flowing through hoppers, are readily shreddable into strong continuous shreds on a consistent basis using shredding rolls and the baked product is free of white streaks or white spots. The process can be conducted continuously without a tempering step which reduces operating and equipment costs. Additionally, material handling equipment, shredding equipment, and baking equipment conventionally used in the production of shredded wheat can be used in the process of the present invention. Accordingly, existing plants for the production of shredded whole wheat can readily be adapted to the production of shredded oats without substantial equipment modification.